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Discussion Starter #1
Hello!

This is my first post so here we go!

I have a 1987 Honda Prelude 1.8L dual carb and I am looking for the name of the part that is vacuum line hooks up to. I believe it is a nippodenso part, but it has no label. Also, I was stopped at a stop sign and my idle dropped and the car stalled. It would not start again until I covered the vacuum line and then it idled fine. Could this part be causing an idle issue? I have a picture of the part and highlighted it (it is taped up). I also took a picture of the vacuum diagram and highlight the part I think it is as well.

Thank you!

WARNING: These pictures may be High Res!
 

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Discussion Starter #2
After looking at another thread, I believe the vacuum line that hooks up to this part also hooks up to the igniter module if that helps easier identify the part.
 

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After looking at my picture more thoroughly, I think that part is labeled as Idle air control valve B? Would that be correct and causing my issue?
 

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Discussion Starter #4
27475


Here is another picture taken from another thread. I am asking for help identifying the white part that has a vacuum line connecting it straight to the igniter module (in back of white part).
 

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Hey, the 2nd gen Ludes in America got A LOT of unnecessary stuff under the hood. All emissionstuff. If you don't have to pass an emission test, best thing you could do is remove all that nonsense.

There is a write up one here just search for "vacuum hose removal/clean up" or something like that.

and there is a video on it too 2. to be exact:
Part 1:

Part 2:
 

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Discussion Starter #6
Thanks for the suggestion but I live in CA where I need all of the emissions equipment to pass smog. :(
 

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Hello Pr8lude18,
I have an 87 carbureted 1.8l as well. Nice to see I'm not alone. My car is a non-CA car but has the same part you show. I've had some luck getting odd parts like that from Canadian salvage yards or aftermarket suppliers like J.C. Whitney. If you have a Honda Part no. That helps immensely. A couple things:
1.) Do you drive the car often? I don't drive mine in the winter. When I get it out in the spring, it takes a couple of tank fulls of gas through it before all the systems start to act "normal".
2.) My car also has the problem with dying at idle. Seems mostly in warm weather. When you say "covered the vacuum line", which one do you mean, specifically? As you've noted, there are many.

I apologize if some of this is simplistic to all reading. I am new to the forum.
 

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Discussion Starter #8
Hi 87original owner,
Sorry for the late reply. This car I start up and drive often but not too far as I've been dealing with float issues but I will be having the carb rebuilt this week. I have filled up the car once, but Im curious as what you mean by it taking a "couple tank fulls of gas to act normal"? For my car, I had an issue where the car would start up cold and idle steady (although a little high). But, after driving, It would flood and be difficult to start. But, Im guessing you store your car since you don't drive it in the winter, so likely it sitting for that period may be the cause of some of your issues. With these dual carbs, it seems they can be very problematic if they sit too long. To be fair though, that's with any carbureted engine.

To answer your second question, that part turned out to be an emissions air filtering device. When I said I "covered the line" I meant I plugged it as the line didn't fit on the post of the filter as it was broken off. But that didn't solve my issue of the car starting. Turns out it was a bad distributor. Prelude and Honda owners in general likely know of the difficulties finding good distributors for these cars. Likely though, your dying idle is coming from a vacuum line leak. Luckily yours is a Non-CA car so you probably have far less vacuum lines than me. You could buy a hand pump to test your lines to see if they have leaks. My car is sensitive to even one line unplugged and the idle will go up. But, if you are having problems like you said after the car sits for a season, your warm weather idle issue could be a carb issue. Have your carbs been rebuilt?
 

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Hello Pr8lude18,
The shortest version of the story to reply to your questions. A number of years ago, when I started the car after it had been stored for the winter, one of the carb floats had developed a leak, unknown to me until I tried starting it. This flooded one or more of the cylinders to the point that it caused a hydraulic lock severe enough to blow the head gasket, or so we theorize.

So, over the following two plus years a lot of work was done on the car to fix the damage and clean up/overhaul old and original components. Cylinder heads were rebuilt, an overhauled set of carbs were acquired. Likewise for the distributor, spark plugs, wires, Radiator, water pump, A/C system, fuel tank and system. You get the idea. At the end of it, say for the last year, it's been running pretty well, all things considered. My garage is just big enough I can store it inside through the winter (MN). I have made it a priority to start it frequently during the winter and let it come up to temp for 20-30 minutes. Moral of the story, if you're having float issues, get the carbs overhauled sooner rather than later!

With the exception of the one float flooding, I have had very good luck with the dual carb system in the 33 years I've owned the car. A lot of folks haven't. And BTW, the pneumatic/ vacuum line diagram in my non-CA car actually looks a lot like yours. I am convinced that the only person who really knows how that system works is the guy who designed it. But right after he signed his name to the plans, the guys in the white coats came and hauled him off to the nuthouse. Bottom line, it works, but no one knows how.

As far as my comment about the tank fulls of gas. At the conclusion of the work (above), the car just didn't "feel" right until I had run about three thankfulls of gas through it over that summer. Apologies for being so subjective. This year, I started with a can of Sea Foam. It didn't seem to like it much. Now that I have a fresh tank of non-oxy 92 octane in it, it's running as well as its going to. Point being, all the little valves, relays, solenoids last longer and work better if they are used/exercised regularly rather than just idlely stored. When the weather breaks up here and the roads dry off, I take it out and drive it 50 something miles on the freeway, making sure not to shut it off till I get back home, haha.

All this is probably more than you want to read so I'll end it here. I will follow your advise and get a hand pump/vacuum gauge.

Let me know how it goes after you have your carb work done. Cheers.
 

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Discussion Starter #10
Wow that is so cool you are the original owner of the prelude. What made you purchase a prelude back in 1987? Was it the first honda you purchased as well? I just got this one from a guy, but he didn't know its history. I ended up finding the original owners name and address in the manual. I googled her info and got her number. I called her to let her know that 33 years later, he car is still going! I asked her a few questions about the cars history and really enjoyed that experience. I really do love this prelude as it is such a unique car and driving experience. Plus, in my area you don't see many (or any) 2nd gens around. Maybe some of the issues you are experiencing with the car could be carb related or just the nature of the vehicle after that mishap. With cars these old, there is always something to fix haha. I have heard though that running higher octane gas in older cars is recommended as a friend told me that is what her mechanic recommend to her in her older honda. You said that when you drive the car, you make sure not to shut it iff until you get home, I know that feeling as I had carb issues like I said and it would prove very difficult to turn the car on if it stalled or I turned it off. I believe I also read somewhere that someone recommended a rebuild of these carbs every 5 years. For me, mine were rebuilt 6 years ago, so I guess it is time.
 

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Honda had a good reputation for cars even back then. When I saw that they had updated the body style (85-87) to our 2ed gen, I was hooked. I had to have one. I waited to 87 because, frankly, I couldn't afford one until then. Just lucky for me that was the last year of that body style. But beauty is in the eye of the beholder. When I would see one in a parking lot, I would walk 360's around it. From every angle, it looked great. Something I call "classic lines". Then I was able to borrow one for a whole afternoon. Wow did it drive nice for its size and power. That night I started figuring out what the payments would be! The other thing that sets it apart is the ride and handling. Again, something I call "control harmony". The pressure required for a given response from the petals, gear shift, and steering is all so well balanced. Unlike my V6 GTI, with very light gas and brakes, very heavy clutch and gear shift. BTW, the last thing I did to mine before I said project complete was a new set of tires. What a difference that made! Where the rubber meets the road really does mean something.

So cool you found the original owner! Sometimes people approach me and tell me they had one long ago, and loved it. There are a couple up here in the Twin Cities. I've always babied mine. It only has 119,000 miles on it. When I take it to the dealer, everybody stops what they're doing when I drive in. Mostly the car is older than anyone in the building. Then they can't move the car because they don't know how to drive a stick.

I would highly recommend premium non-oxy gas for it, if you can get it in your area. Anything less and mine starts to ping. And I'm sure you're right, the age of everything is a factor. its mostly just that first time out where I don't turn it off. After that, it's good mostly. Mine doesn't like the heat. Middle of the summer I could swear I'm getting vapor locked, which never happened before. Probably not a bad idea to have the carbs rebuilt every so often. Provided you can find someone qualified to. Let me know how yours turn out. And which shop you used. I've got the names of a couple if you need them.

Good luck, Cheers!
 

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Agreed that the Prelude looks good at all angles. The car is just so right! Im not surprised your Prelude gets so much attention. I believe the 2nd gen was the most sold generation of Preludes, so many likely owned one, knew someone who owned one, or aspired to own one. Ill have to look into non-foxy gasoline. I usually get gas at Costco and they use ethanol. I just dropped off my car at the carburetor specialist's, so hopefully all goes well.
 

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I would be interested in what your carburetor specialist says. I heard second hand that the plastic floats in the Honda carbs don't like ethanol. Non-oxy from a name brand station I was told was best (Shell, Mobil, Texaco, etc.). What is the name of the shop, Carburetor Specialist's?
 

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Yes, I dropped it off today but I also wanted them to replace the PCV valve since they will have better access to it. The location of it is hard to reach with all the vacuum lines and carbs on. I was worried they wouldn't find or have the proper kit to rebuild the carb but we will see. The shop is just a small local one called Alamilla's Carburetor here in OC. I have several other shops I know (2 in particular that deal with Hondas). Hopefully, I won't need to call them. My dad told me that when he asked for them to rebuild the carbs, they said "that is a very expensive job." "How much?" my dad asked. "About 500 bucks." they said. There was another shop I wanted to the it to and they charged 130 dollars just to inspect the car. If 500 rebuilds the carbs, Im perfectly fine with that! I was thinking I was having float issues, but I heard floats for these carbs are hard to come by. But, I also heard that some model of the Honda Goldwing uses similar floats.
 

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That sounds about right. I bought a rebuilt set, the ones that are on the car now, from a place in California for $600. If they have the know how to do it, it's worth it. The floats are nearly impossible to find any more. It took me a year and a half to find a set, from JAPAN! Six weeks to get here. I have heard the same about the Honda Goldwing. The Part number has only one digit that's different because it's a motorcycle part, but it's suppose to fit. I would be curious to hear what your guys say to all this.
What keeps it running? It only takes money!?
 

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Discussion Starter #16
Definitely right that money keeps it running haha. I will check in with the mechanics and let you know. Ill have to look up what Goldwing bike is said to be a match, just in case.
 

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I have a question for you. When you fill up your tank or drive around and release the gas cap, does it hiss like its releasing pressure? My dad found this worrisome until I confirmed this was normal with some other Honda people. He thought that maybe that could have been causing the car to overflow as maybe a return line was clogged or something in the tank. Im pretty sure it was something in the carb (floats maybe) sinking and causing it to overflow.
 

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I went to the mechanic today to drop off the PCV valve for him to replace. He showed my dad and I the floats, and they were jerry rigged with wire to hold them together and onto the bracket. It looks like the previous mechanic who worked on this tried to fix the floats because he couldn't find new ones. Luckily for me, the carburetor specialist had a brand new set of floats and he told my dad that we were lucky that he had them haha. But he cleaned and polished the carbs and they look really great! I took a few pics to show you and so I could view them later. It looks kinda scary with everything apart, but hopefully it all goes back together smoothly.
 

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You can see the floats have like wire going through them to hold it together. I thought they would be made out of plastic, but its kind of like a cork material.
 

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You can see the floats have like wire going through them to hold it together. I thought they would be made out of plastic, but its kind of like a cork material.
Hi Pr8lude18,
Sorry I didn't reply sooner. Never got an email from the forum site about your gas cap question. Yes, it is normal, at least for the last 33 years, that the tank vents a little when you remove the cap.

As far as the floats, it's probably too late now but I would like to see a picture of the ones your guy put in. I will try to upload a picture of my original ones that were sorta repaired. Note very carefully the position of the metal tab on the bracket the holds the floats together. The correct floats have the metal tab mounted on the inside, pointing out toward what looks like a pivot tube. There are some on the internet that look identical but have that metal tab mounted on the pivot tube pointing inward. I was told by a highly qualified carb guy those floats will not work.

The picture of my repaired ones. You can see where the leak in the float was patched. Please disregard the VW key fab. It was for size comparison.
IMG_4837.JPG
 
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